Planting Your Pond
Nearly all ponds will benefit from having a good selection of plants, not least because they give the area a more natural and informal feel.
Although is may seem obvious, aquatic plants are different to land based plants, because they have evolved to live in wet even submerged conditions. There are three principle groups of aquatic plants, all with specific needs.
Pond Plants serve many other useful functions
- They attract wildlife to the pond, providing food, rest and breeding sites for a host of creatures.
- They improve the aesthetics of the pond, breaking up hard edges and bringing colour to the area.
- They are used as spawning sites by pond fish and other creatures.
- They offer fry and other baby creatures food and protection.
- They produce oxygen and use up carbon dioxide.
- They shade the pond, providing cover for the fish and preventing excessive algal growth caused by high light levels.
- They remove nutrients from the water, which would otherwise build up and encourage the growth of algae.
It is therefore not only aesthetically pleasing, but also beneficial to the pond environment to have a good selection of pond plants.
Marginal & Bog Plants
These are essentially the plants that stick up above the surface of the water and provide height to the pond. They can be planted into waterlogged ground or more commonly into plastic planting baskets, which are then placed into the water.
Marginal plants are those which are suited to shallow areas of the pond, although there are a few that will tolerate deep water (these are normally marked as “deep water marginal”). Generally, they can only cope with having a few inches of water covering their containers, and therefore a special marginal shelf is usually incorporated into the pond to accommodate them. This shelf should be around 30cm (1ft) wide, and about 20 – 23cm (8in or 9in) deep.
Marginal plants come in all shapes and sizes, from tall grasses and irises to low, creeping varieties. They can provide shelter from the wind and a safe refuge for all manner of pond life. Taller varieties can also help to shade the pond, although this is best done with floating leaves.
6 - 8 inches (Although most marginals are better planted with the water level with the top of the pot)
Plant into planting baskets using aquatic compost, when the plant starts to die back in the autumn, cut back the plant to ensure that the decaying plant material does not pollute the water. Feed once a season with an aquatic root fertiliser.
Generally these plants can be cultivated by division in the spring, although because of the huge number of plants in this sections it's best to consult your nursery.
These floating plants have extensive root systems that dangle into the water from the surface, these root systems provide ideal spawning areas for fish like goldfish. They often reproduce by budding and as such can be very invasive.
Floating plants are usually only available in the summer, as they do not over-winter particularly well. The majority of them will either require replacing every year, or over-wintering indoors in a bucket of water. There are quite a few varieties of floating plant available, such as water hyacinth, water soldier, frogbit, water chestnut. Their root systems dangle in the water and provide good spawning sites for pond fish, as well as extracting nutrients from the water that would otherwise encourage algae. They are very useful for providing shade for the pond, as well as offering a home for invertebrate life upon which the fish may feed.
Allow to float unplanted on the surface
They only care required is for tender variety if they are needed the following season. Take a strong plant in the early autumn and keep in pond water in a well lit frost free greenhouse. Periodically replace the water with fresh water. Stratiodes (the water soldier) sinks to the bottom of the pond in the winter and rises again in the spring.
These are plants that are not very visable, as they are present under the water. But they can fulfil a useful role in the pond. They absorb nutrients, and can help to reduce the growth of algae in the pond. Calling them oxygenators can be a misnomer as although they produce oxygen during the day, they absorb it again at night. Oxygenation is best achieved using a pond pump.
Oxygenating plants, such as Canadian pond weed and water milfoil, are so called because they produce oxygen during the day as a by-product of photosynthesis. Their name can be a little misleading, as at night they stop producing oxygen, yet they continue to respire and use it up. In a moderately stocked pond, the amount of oxygen used up at night is not usually a problem, and they benefit the pond environment by providing good spawning sites for fish and other creatures.
They also create a refuge for fish fry and other small pond creatures, and provide homes for a variety of invertebrates which fish like to eat.Their rapid rate of growth also makes them ideal for natural algae control.
Oxygenating plants often come in bunches, and should be added to the pond at around 5 bunches for every square metre of surface area. They will need occasional pruning to keep their growth under control. It is often easier to plant bunches of oxygenating weed in a pond basket, as this keeps them in one place and allows them to be more easily removed if necessary.
Up to 18"
These plants are usually purchased in clumps unpotted, and they do best when they are potted into planting containers with aquatic compost and dressed with pea gravel. Depending on the size of the container you should get 3 - 6 bunches per pot. You should have one bunch for every 2sq feet of pond surface.
When the plant becomes too big, simply cut a length off and plant up into a fresh container.
Anacharis, hornwort, cabomba.
Deep Water Plants
These plants have leaves that float on the surface and roots that are firmly placed in containers on the bottom of the pond. Water lilies are generally the best known aquatic plant. They are available in an enormous assortment of varieties and ).colours. Water lilies and other lily-like plants grow in deeper areas of the pond, sending up leaves to the surface. These floating leaves are ideal for shading the pond, and fish will often bask under them on hot, sunny days. You should aim to cover around a third to one half of the pond with floating leaves (floating plant varieties can also be used to do this). If you are just using water lilies for the deeper sections of the pond then they can be planted at a rate of one for every 1.5 – 3m of surface area (the exact amount will depend on what size the lilies are)
There are many different varieties of water lily, ranging from small pygmy strains, such as Nymphaea ‘Pygmaea Helvola’ which has a maximum spread of 60cm (2ft) and is happy in less than a foot of water, to very large ones, such as Nymphaea tuberosa ‘Richardsonii’ that can have a spread of 2.7m (9ft) and needs a depth of 90cm (3ft). Lilies tend to start flowering when the water temperature exceeds 18ºC, with the blooms getting steadily more impressive as the season progresses. Each bloom tends to last around 4 days, with the flower opening in the morning and closing again in the evening.
There are two approaches to the introduction of lilies to the pond, the first being the more traditional approach:
1. Lower the lily to its final position in the pond slowly, starting off by covering it with only 15 – 25cm (6 – 10in) of water. It can be supported on bricks or upturned baskets, lowering it by around 15cm (6in) at a time over a period of a year or so. This is done because lilies do not adapt well to sudden changes of depth, the effects of which can include checked growth, small leaves and poor flowering.
2. Alternatively you can cut the lilies foliage back to its crown and place it at the bottom of the pond. New growth will then start to appear in the following weeks and months.
If you plan to plant the lily very deeply then it may be advisable to stick to method one, but in shallower ponds either approach should work. When selecting your new plants there are a few things to look out for. The best ones are those that show signs of new growth, and that are not damaged or stunted. It is also wise to look out for signs of pond snails or eggs (which appear as clear jelly-like masses attached to leaves), and wash them off before the plant is potted up.
Variable up to 3'
These plants should be in water that is at a depth specific to the variety in question. They should be planted in a generously sized container rich in nutrients, the compost should be covered with Pea Gravel and larger stones. If this does not prevent your fish from digging up the compost in their quest for food, then try enclosing the whole container with an old pair of nylons. These plants need regular feeding if they are to flower prolifically throughout the whole season. Dead leaves and flowers should be removed or else they will rot and pollute the water.
The lilies can be propagated by cutting sections from the rhizome, and planting in fresh compost . This should be done when the plant is entering the growing phase, not at the end of the season.
Moisture Loving Plants
Moisture loving plants are those that require permanently damp soil, but that will not do well in any depth of water. They are ideal for bog gardens and can add a whole new dimension to the pond, often attracting all sorts of wildlife to the area. Some varieties of plant will do equally well on a marginal shelf or in a bog garden, and so it is important to check information labels to see exactly where you can put a particular plant. Bog garden plants are best moved and divided during either the spring or autumn, and in the spring the soil can be perforated and the area given a general tidy up. Autumn is a good time to dig over the soil, so the winter frost and rain can break it down for the spring. Moisture lovers are not planted in pond baskets like other aquatics, but instead placed directly into the bog garden soil.
The best way to give your new plants a healthy start is to re-pot them, replacing the soil they come in with a good quality aquatic compost. Cascade Pond Soil has a high loam content that prevents clouding of the water, and a slow release fertiliser that encourages lush plant growth, whilst discouraging the growth of algae. It is also fully sterilised to prevent the introduction of pests and diseases. New plants should be housed in baskets that are large enough to allow for expansion. The larger the container they are in, the longer it will be before they need re-potting.
The reason aquatic plants must be placed in perforated containers, and not ordinary flower pots, is that their root systems need a flow of water to them in order to supply nutrients and oxygen.This aeration of the soil prevents it from becoming anaerobic (depleted of oxygen) and foul smelling.
Once you are ready, you can plant up your aquatic plants using the following procedure:
- If you are using an ordinary pond basket, line it with hessian to prevent compost leaching into the water. If you are using an AquaPlanter, open it up ready for filling.
- Start filling the basket or AquaPlanter with aquatic compost, firming it as you go.
- Remove the plant from its original pot, make room for it in the compost and place it in its new container.
- Firm more compost around the plant and add water to it in order to drive out any trapped air. This may cause the compost to sink slightly, in which case more should be added.
- The compost should then be topped with around 1 – 2cm (0.5 – 1in) of hard gravel or pond flint, in order to stop the fish from digging into it, and to stop it lifting out of the container when it is submerged.
Ordinary soil or garden compost should not be used as it is unlikely to contain the correct balance of nutrients required by aquatic plants. It is also likely to encourage excessive algal growth and can contain contaminants that might be harmful to pond life. The same method can be used for re-potting plants when they out-grow their containers. At such times the plant can either be divided up and planted in the same sized container, or simply moved to a larger one. With water lilies, make sure that you use a large container, with at least 15cm (6in) of compost. When you re-pot them it is very important to place the growing tip (or “crown”) so it is exposed to the water, and in the same position as it was in its original pot.